Chair Foot Ring Bush Structure for Adjustable Post Clamping
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Solution Overview
Problem
Conventional foot ring fixing structures for chairs suffer from complex designs and uneven force distribution, leading to reduced clamping force and difficulty in adjusting the height position of the foot ring.
Innovation Solution
A simplified structure featuring a bush with a tapered outer surface and internal threads, which is assembled with a hub having internal threads, allowing for easy assembly and adjustment of the foot ring's height by rotating the bush to clamp or release the supporting post.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a straight-shape pressing sheet is used in the clamping ring, then the structure is simple, but the force distribution is uneven and clamping force is reduced
Solution Approach 1:
The pressing sheet is designed with an arc shape that matches the curvature of the clamping ring's inner surface, allowing it to conform to the circular geometry. This curved design enables the pressing sheet to distribute force evenly around the clamping ring when actuated by the screw, resolving the contradiction between structural simplicity and effective force distribution.
2Adaptability or versatility
If a clamping ring with a slot is used to allow height adjustment, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The clamping ring is divided into two functional parts: the ring body with a slot that allows vertical movement for height adjustment, and the pressing mechanism with an arc-shaped pressing sheet that provides clamping force. This segmentation allows the height adjustment function to be independent from the clamping function, simplifying the overall design while maintaining both adjustability and secure fixation.
3Ease of operation
If a screw mechanism is used to control clamping, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The screw mechanism is integrated directly into the hub of the foot ring, allowing the user to operate the clamping function through a single knob without requiring separate external mechanisms. The screw threads engage with the hub's internal threads, creating a self-contained clamping system that is both easy to operate and structurally simple.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a simple, easy-to-assemble, and adjustable foot ring fixing structure that ensures a stable and firm mounting of the foot ring on the supporting post, allowing for effortless height adjustments.
Implementation Method 1
the bush has a tapered outer surface... when the bush rotates toward a first direction, the wall of the bush is restricted by the central hole and the inner diameter of the shaft hole is reduced to clamp and fix the supporting post
Implementation Method 2
the bush is assembled with the hub by screwing the external threads of the bush with the internal threads of the hub
Implementation Method 3
the two pads are softer and have a higher coefficient of friction compared to coefficient of friction of the inner surface of the shaft hole
Data Source
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AI summary
Provided is a fixing structure for a foot ring of a chair, including: the foot ring having a hub with a central hole formed with internal threads on an inner surface thereof; and a bush being a cylindrical body having a tapered outer surface with external threads formed thereon. The bush has a shaft hole penetrating along a longitudinal axis of the bush, a groove penetrating through a wall of the bush, and at least one pad provided on an inner surface of the shaft hole of the bush. The bush is assembled with the hub by screwing the external threads of the bush with the internal threads of the hub. A supporting post penetrates through the shaft hole of the bush. When the bush rotates toward a first direction, the shaft hole is reduced to clamp and fix the supporting post, and when the bush rotates toward a second direction, the shaft hole is enlarged to release the clamping and fixing of the supporting post.